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Methylation of gene promoters or coding sequences is a common method of gene silencing and can be under genetic and/or epigenetic control. This is one of several mechanisms in how plants/animal/microbes manage gene expression. As you know, this is an exciting and emerging field in biology/genetics. The roles of micro-RNAs and transcription factors in regulating individual genes and/or whole metabolic pathways is now probably better understood in humans than in plants - but the principles are very similar. Rin is a classic transcription factor that regulates, directly or indirectly, several different processes in tomato fruit - together controlling the fruit ripening process. Methylation/silencing of specific genes may be involved - but not sure. The recessive loss-of-function mutant "rin" results in a non-ripening phenotype, as does alc/alc, but as noted in the photos above there are other phenotypic traits that are quite different between these two mutants - thus my interest.

I'm glad I did bring up the subject of DNA methylation as a transcription controller b/c now I know more about rin and for sure there will be more information in the future,'

Notice under traits that it's considered a longkeeper and the thinking is that there was a single pleiotropic mutation that affected many other genes at the same time that led to the many changes in leaf color and transition of different colored fruits as part of the ripening process. Maybe Google IMAGES shows that

Yes, I've grown it and the final red fruits are NOT good tasting at all.

There are other tomatoes also known as lonngkeepers but I don't think anyone has done anything with them biochemically

I suppose my own DNA is also methylated and if so I know which of my genes I'd like shut off and also some that I'd like activated.

As it is, I've been saying for a couple of years that I want to participate in the National Geographic Genome Project. You pay your money, not cheap, and are sent a kit for you to take saliva swabs and send them in. Not for medical reasons, rather to find out which percentage of your DNA corresponds to which area on earth, whether Northern European, Micronesia, African, etc. And going back thousands of years to early man, denisovan, and whatever and I really should do that,

This weekend a mutual friend introduced me to one of the commercial breeders that introduced and developed EFS (extended field storage) processing tomatoes. Today we chatted for almost an hour. EFS is substantially equivalent to the Alcobaca mutant alc, but with added tolerance to post harvest fruit rotting organisms and better cracking tolerance. EFS and alc are both allelic to nor - but both with a distinctly less severe "non-ripening" phenotype in the homozygous state. Moreover, the odd plant/fruit that I found (photo earlier in this post) looks to be homozygous at both the alc and ogc (crimson) loci - thus the crimson flesh combined with the dull yellow unripe outward appearance of the fruit. This summer I crossed this alc/alc - ogc/ogc plant to a few early striped grapes and cocktail types - F1s in the greenhouse this winter. Based on what I have learned, I think this may be an interesting, and novel, path to extended shelf life fresh market tomatoes. Next summer I'll cross to my best crimson beefsteak types derived from Tasti-Lee and Mtn Merit.

Last edited by frogsleap farm; December 7, 2015 at 11:31 PM.
Reason: second thoughts

Here is fruit from a F1 plant in one of the crosses I made with the EFS plant described above. As I had suspected, the EFS gene in the heterozygous state gives a normal phenotype with exceptional shelf life. Flavor was very good, especially considering one of the parents was a commercial paste type. More detail on extended shelf life strategies here:

Excellent blog post, and very thorough, thank you so much for sharing what you found.
There's been a lot of talk about the 'de colgar' varieties lately, and piqued my interest, although there's little chance of "dry cultivation" here I may have to try them.
Also I had never even heard of dfd and the EFS.
More tomato mysteries, revealed.